1. Field of the Invention
The present invention relates to an electromagnetic driving device used in a camera for a mobile phone, in particular to an electromagnetic driving device capable of lens driving and with image stabilizer function.
2. Description of Related Art
In recent years, for a camera in a mobile phone, pixel count of an image sensor is increased so as to lead a high image quality of images. At the same time, a lens system loaded in the camera is also being transferred to a lens driving device with movable focuses from an existing lens driving device with fixed focuses. This is because that defocus appears in the lens driving device with fixed focuses and the resolution ratio of the image sensor with high pixel count cannot be responded.
As the lens driving device with movable focuses, most lens driving devices use voice coil motors (referring to Patent Literature 1: JP Patent No. 2004-280031, for instance). However, in the view of preventing shaking appearing easily during shooting, for the camera loaded in the mobile phone, an optical device for shooting, in Patent Literature 2: JP Patent No. 2009-294393 for instance, is provided.
In the optical device for shooting in Patent Literature 2, a movable frame loaded with the lens driving device and the image sensor is mounted to be capable of swinging relative to a fixed frame, a magnet for swinging the movable frame is mounted in the movable frame, and coils for swinging the movable frame are mounted in the fixed frame. Moreover, by electrifying the coils for swinging mounted in the fixed frame, the movable frame can swing relative to the fixed frame so as to inhibit (hand) shaking.
Moreover, the optical device 50 for shooting as shown in FIG. 12 is provided with a first coil 52a for lens driving and a second coil 52b for lens driving which are wound around the Z axis of the direction of the optical axis of the lens (an arrow as shown in figures) and are mounted on the lens support 51, a first magnet 54a for driving and a second magnet 54b for driving which are mounted on the inner side box body 53, are respectively partitioned at an interval and are mutually arranged opposite to the first coil 52a for lens driving and a second coil 52b for lens driving, and four coils 56 for swinging which are wound around the axis orthogonal to the Z axis and are mounted inside the outer side box body 55. The optical device 50 for shooting is used for driving in the direction of Z axis by utilizing the first and the second magnets 54a, 54b for driving and the first and the second coils 52a, 52b for lens driving, and is used for swinging the inner side box body 53 around the axis orthogonal to the Z axis by utilizing the magnets 54a, 54b for swinging and the coil 56 for swinging, and thus the hand shaking is corrected. Moreover, the optical device 50 for shooting is used for driving the lens and inhibiting the shaking at the same time by the magnet 54a for driving and the magnet 54b for driving, and thus the optical device for shooting like this can be miniaturized than Patent Literature 2 (in Patent Literature 3: JP Patent No. 2011-203476, for instance).
However, the optical device 50 for shooting in Patent Literature 3 needs the coil 52a for lens driving and the coil 52b for lens driving which are wound in opposite directions mutually. Moreover, the optical device 50 for shooting uses the following components respectively: the first and the second coils 52a, 52b for lens driving which are wound around the Z axis and are mounted on the lens support 51, the first magnet 54a for driving which is arranged opposite to the side 56a of the shot side of the coil 56 for swinging, a second magnet 54b for driving which is arranged opposite to the side 56b of the opposite side of the shot side, wherein the polarity of the second magnet 54b for driving is different from that of the first magnet 54a for driving, and thus the amount of the coils for driving and permanent magnets is increased. And then, the optical device 50 for shooting is such disposed that the coils 56 for swinging and the first and the second magnets 54a, 54b for driving are partitioned at intervals and are arranged opposite to one another, and thus the size in the orthogonal direction of Z axis is increased, and further miniaturization is further limited.
Moreover, in the optical device 50 for shooting in Patent Literature 3, only two sides 56a, 56b of the coils 56 for swinging are subjected to the effect of Lorentz force, and thus the problem of insufficient driving efficiency also appears.